Trunnion valve for continuous rotary filter

ABSTRACT

IMPROVED TRUNNION VALVE FOR ROTARY FILTERS PROVIDING A BRIDGE PLATE ASSEMBLY HAVING SIMPLE AND COMPACT MEANS FOR ADJUSTING THE BRIDGE BLOCKS FROM THE OUTSIDE, THEREBY VARYING THE EXTENT AND LOCATION OF RESPECTIVE OPERATING ZONES OF THE FILTRATION CYCLE WITHOUT NECESSITATING THE DISMOUNTING OF THE VALVE.

TRUNNION VALVE FOR CONTINUOUS ROTARY FILTER Original Filed Doc. 20, 1967April 11, 1972 J. A. SHEAFFER 5 Sheets-Sheet 1 FIG. 3

INVENTOR. JOHN A. SHEAFFER BY Qfiwwe ATTORNEY.

April 1 1, SHEAFF'ER Re.

TRUNNION VALVE FOR CONTINUOUS ROTARY FILTER Original Filed Dec. 20, 19675 Sheets-Sheet 2 INVENTOR.

JOHN A. SHEAFFER ATTORNEY.

April 1972 J- A. SHEAFFER Re. 27,326

TRUNNION VALVE FOR CONTINUQUS ROTARY FILTER Original Filed Dec. 20, 19675 Sheets-Sheet 5 INVENTOR. JOHN A. SHEAFFER ATTORNEY.

April 11, 1972 J E R Re. 27,326

TRUNNION VALVE FOR CONTINUOUS ROTARY FILTER Original Filed Doc. 20. 19675 Sheets-Sheet 4.

INVENTOR.

JOHN A. SHEAFFER ATTORNEY.

April 1 1, 1972 AFFER Re. 27,326

TRUNNION VALVE FOR CONTINUOUS ROTARY FILTER 5 Sheets-Sheet 5 OriginalFiled Dec. 20, 1967 INVENTOR- JOHN A. SHEAFFER ATTORNEY.

United States Patent 27,326 TRUNNION VALVE FOR CONTINUOUS ROTARY FILTERJohn A. Sheafi'er, South Norwalk, Conn., asslgnor to Don-OliverIncorporated, Stamford, Conn. Original No. 3,455,454, dated July 15,1969, Ser. No.

692,085, Dec. 20, 1967. Application for reissue Oct. 1, 1969, Ser. No.868,248

Int. Cl. 801d 33/08, 33/06, 33/02 US. Cl. 210-91 42 Claims Matterenclosed in heavy brackets appears in the original patent but forms nopart of this reissue specification; matter printed in italics indicatesthe additions made by reissue.

ABSTRACT OF THE DISCLOSURE Improved trunnion valve for rotary filtersproviding a bridge plate assembly having simple and compact means foradjusting the bridge blocks from the outside, thereby varying the extentand location of respective operating zones of the filtration cyclewithout necessitating the dismounting of the valve.

This invention relates to continuous rotary filters having an assemblyof filter chambers mounted to rotate about a horizontal axis on a pulpcontaining vat.

This class of filters may include disc type filters, drum filters havingthe filter media attached to the drum, as well as belt-type drumfilters, all of which have a trunnion at the end of the rotatableassembly, provided with internal filtrate discharge ducts spaced aboutthe axis, and extending from the vertical end face of the trunnion tothe respective filter chambers.

More in particular, this invention relates to improvements in theso-called trunnion valve containing the socalled bridges or bridgeblocks which cooperate with the end face of the trunnion and thefiltrate discharge ducts in controlling the phases or zones of thefiltration cycle.

The operating zones in the filtration cycle may require adjustments ofthe bridge blocks, to be effected for example during start-up or to meetchanging conditions in the filter operation.

One object of this invention therefore is to provide simple, practical,and compact means for independently adjusting the position as well asthe effective arcuate extent of the respective operating zones in thefiltration cycle. More particularly, these adjusting means should beoperable in a manner which avoids the previous cumbersome necessity ofdismounting the trunnion valve to gain access to the bridge blocks sothat they might be repositioned or exchanged.

In its simplest form the operating cycle itself may comprise a vacuumcake forming or pick-up zone effective during submergence of the filterchambers in the pulp; vacuum cake drying zone subsequent to the cakeforming zone, efi'ective after emergence of the filter chambers from thepulp; and a neutral zone following the drying zone to allow filter caketo be discharged before re-irnmersion of the filter chambers in thepulp, and extending down to the starting point of the submerged cakepick-up zone.

A single source of vacuum may serve both the cake formation and the cakedrying zone. But if a wash liquid be applied to the filter cake afteremergence, then a second neutral zone may be interposed between the cakeforming zone and a combined cake washing and drying zone, in order thattwo filtrate fractions may be collected in separate receivers. Acorresponding additional bridge block providing an interposed neutralzone, and cooperating with corresponding additional partitioning meansin the stationary valve member will provide for such a fractionation.

Furthermore, where indicated, filter cake discharge may be assisted bythe inclusion in the filtration cycle of a blow-back zone interposedbetween two neutral zones functionally separating the blow-back effectfrom the preceding drying zone and from the subsequent cake forming orpick-up zone.

Normally, two critical points in the filtration cycle requiringadjustment independent of each other are the starting point of the cakedischarge zone and the starting point of the cake pick-up zone.

According to this invention, independent or universal adjustment of theoperating zones is made possible conveniently by the provision of avalve plate assembly in face to face relationship with the end face ofthe rotating trunnion and with the stationary valve member. In thisassembly, the adjustable bridge blocks are mounted in a valve platemember, each block having a stem or bolt extending radially outwardlythrough a slot in the peripheral rim portion of the valve plate member.The slots are coextensive with the periphery, thus allowing for angularadjustment or positioning of the blocks in the valve plate member aboutthe filter axis. The blocks are secured in adjusted position by thetightening of the radial bolts.

According to the invention, the extent and location of the operatingzones of the filtration cycle may be varied by the provision of meanswhereby the valve plate itself together with the blocks is rotationallyadjustable even while the blocks are individually adjustable.

The invention also provides novel practical indicator means that areeasily applicable, to provide a measure of the setting of the bridgeblocks when in operation, and also designed so that the setting may berestored in case the valve is taken down for overhaul.

Other features and advantages will hereinafter appear.

FIG. 1 is a side view of a continuous rotary disc filter with thetrunnion valve embodying the invention.

FIG. 2 is a view upon the valve end of the filter, taken on line 22 ofFIG. 1.

FIG. 3 is an enlarged side view of the trunnion valve, showing thebridge plate assembly embodying the invention.

FIG. 4 is an exploded view of the trunnion valve of FIG. 3, showing thebridge plate assembly separated from the associated parts.

FIG. 5 is a cross-sectional view taken on line 5-5 of FIG. 4, showingthe end face of the trunnion.

FIG. 6 is a cross-sectional view taken on line 66 of FIG. 4, showing oneside of the bridge plate assembly according to one embodiment thereof,including various adjustment indexing means.

FIG. 7 is a sectional view of the bridge plate assembly, taken on line7-7 in FIG. 6.

FIG. 8 is a sectional view of the bridge plate assembly, taken on line8-8 of FIG. 6.

FIG. 8a is an enlarged detail view of indexing means from FIG. 8.

FIG. 8b is a view taken on line 8b8b in FIG. 8a.

FIG. 9 is a view of the opposite side of the bridge plate assembly ofFIG. 6, taken on line 99 of FIG. 4.

FIG. 10 is a view similar to FIG. 6 of a bridge plate assembly embodyingthe invention in a modified construction.

FIG. 10a is a detail sectional view taken on line 10a- 10a in FIG. 10,showing another form of indexing means.

FIG. 11 shows the opposite side of the bridge plate assembly of FIG. 10.

The invention, by way of example, is herein shown embodied in a discfilter generally illustrated in FIGS. 1 and 2. Accordingly, an assemblyof filter chambers rotatable about a horizontal axis comprises a seriesof filter discs mounted upon a filter shaft 11, in horizontally spacedrelationship to one another. The trunnion ends 12 and 13 of the shaftrotate in trunnion bearings 14 and 15 mounted upon respective end walls14a and 15a of a vat 16, so that the lower portions of the discs will beimmersed into a body of pulp in the vat.

Each filter disc in turrn constitutes an assembly of sector-shapedfilter chambers 10a (see FIG. 2) having filter media mounted thereon atboth sides. Each sector of each disc registers horizontally withcorresponding sectors of all the other discs, so that there are as manyhorizontal rows of sectors as there are sectors in each disc. Rotationof this assembly about the shaft in the direction of arrow W will causethe filter chambers of each disc to pass sequentially through the pulp.Filter cake collected on the filter discs may be discharged at thedescending side thereof in a conventional manner here not shown, butpreferably employing back-blow to facilitate and expedite cakedischarge.

Within the filter shaft there are provided horizontal filtrate dischargeducts 15a (see FIG. 5) parallel to and equally spaced around the axis.Each of these ducts inwardly communicates with a respective row offilter sectors or chambers, and outwardly terminates in the transverseor vertical end face of the trunnion end 12 of the shaft. This end faceof the trunnion is represented by a conventional wear plate 16b theopenings of which register with the ducts. The rotating trunnion endface 16c cooperates in face-to-face sliding contact with a stationaryso-called trunnion valve T, the vertical plane of working contact orinterface being indicated at F. The opposite end of the filter shaft isclosed. Drive means 12a are indicated at this end for rotating theshaft.

Trunnion valve T controls the filtration cycle incident to the rotationof the filter shaft, so that a pressure differential or vacuum and, ifneed be, back-blow air pressure may be applied to the filter chamber 10awithin respective zones or phases of the filtration cycle. A requiredperiod of submergence of the filter chambers occurs in the cake formingphase, followed by a cake washing and/ or cake drying phase afteremergence at the ascending side of the discs. At the descending side,back-blow acts to detach the cake in the discharge zone.

The improved trunnion valve of this invention as shown in FIG. 3,provides improvements in the bridge plate assembly, controlling thefiltration cycle. FIGS. 3 to 11 derived therefrom will serve in thefollowing description of the invention in more detail.

The trunnion valve according to FIGS. 3 and 4 cornprises a hollowopen-ended manifold or stationary valve member 17 provided internallywith a partition 18 (see FIG. 6) which separates a vacuum supply chamber19 from a back-blow air supply chamber 20 (see FIG. 4), the vacuum beingsupplied through a wide neck 21 and the back-blow air through a narrowneck [22.] 22, providing air supply which breaks the vacuum.

The vertical inner end face 23 of the manifold member (see FIG. 4) hasattached thereto the bridge plate assembly 24 (see FIGS. 4, 6, 9) withthe bridge blocks therein adjustable from the outside for independentlycontrolling the location of certain operating zones or phases in thefiltration cycle without necessitating the dismounting of the trunnionvalve.

In the improved bridge plate assembly according to the embodiment inFIGS. 6, 7, 8, and 9, a bridge plate 25 comprises an outer peripheralrim portion 26, a central hub portion or disc portion 27, and anintermediate arcuate plate portion 28 rigidly interconnecting the rimportion and the disc portion, thus forming a shallow groove 29 of anarcuate length L-l and the width d. The flat bottom of this grooveprovides a flow blocking area A1 complementary to an arcuate throughflowarea or opening A-Z having an arcuate length L-2. Along the arcuatesides of the throughflow area A-2 there are shoulders 30 and 31respectively having faces 32 (see FIG. 7) co-planar with the bottom face33 of the shallow groove. The throughflow area A-2 registers with thevacuum supply chamber 19 of the stationary valve member. The bottom ofthe shallow groove has a backblow opening 34 registering with thebackblow supply chamber 20 of the stationary valve member.

The first or upper bridge block 35 is slidably adjustable in the upperend portion of the shallow groove by way of loosening and tightening thebolt 36 threaded into the bridge block. This bolt extends radiallyoutwardly from the bridge block through a slot 37 provided in the rimportion 26 peripherally co-extensive therewith. Loosening this bolt willallow the bridge block to be shifted in the groove within an arculate orangular range corresponding to the length of the slot. Tightening thebolt will secure the block in the adjusted position. The bolt alsoextends through the curved base plate or body portion 38 of an indexpointer 39 cooperating with a scale 40 provided on an index plate 41which is press-fitted into a peripheral groove 42 (see FIGS. 7 and 8)provided upon rim portion 26. Thus, when the bolt 36 is loosened and theblock is shifted, the pointer will move with the block from one point toanother on the scale, thus registering the amount of angular adjustmentof the block.

The pointer also cooperates with a companion indicator 43 (see FIGS. 6,7, 8, 8a, 8b) mounted upon the index plate, and slideable thereon alongthe scale. This indicator 43 is securable by means of thumb screw 44 orthe like in any adjusted position of the index plate relative to thescale, as well as relative to the pointer.

Following the adjustment of the bridge block, the companion indicator 43may be secured on the index plate in a position registering with thepointer 39. The companion indicator thus provides a reference pointwhereby the amount of angular adjustment is measurable, or whereby anadjusted position of the bridge block may be restored. This bridge blockhas a blowback opening 45 registering with blowback opening 34 in thebridge plate, which latter opening in turn registers with the backblowsupply chamber 20 of the stationary valve member.

A second or lower bridge block 46 is adjustable in the lower end of theshallow groove 29, substantially in the same manner as the bridge block35.

A first fastening means or bolts 47 secure the bridge plate assembly inface-to-face relationship to the stationary valve member 17, thusconstituting therewith a stationary sub-assembly. These bolts extendfrom lugs 48 on the stationary valve member through respective arcuateslots 49 (see FIG. 6) provided on the rim portion of the bridge plate topermit rotational adjustment of the bridge plate assembly as a whole, inaddition to individual adjustment of the bridge blocks.

Second fastening means or bolts 50 in turn hold the stationarysub-assembly in face-to-face relationship with the end face 16c of thetrunnion. These bolts, however, being fixed to, or being threadedtightly into, the trunnion bearing 14, extend through respective lugs 51on the stationary valve member 17. A compression spring 52 surroundingthe outer projecting free end of each such bolt, and confined betweenthe lug 51 and a nut 53, maintains the cooperative face-to-facerelationship between the trunnion end face 16c and the aforementionedsub-assembly or trunnion valve T.

In the embodiment of FIG. 6, the throughfiow area A-Z is subdivided by arib 54 to which is fastened by means of screw 55 a third bridge block 56providing a third neutral zone functionally separating a cake formationzone from a subsequent cake-washing and/or cakedrying zone, each ofwhich zones may be connected to a separate vacuum receiver, in orderthat strong filtrate liquor may be handled separate from the weak liquoror spent wash liquid. Accordingly, the vacuum chamber 20 in thestationary valve member is provided with a further partition 57 (seeFIG. 6) dividing it into vacuum chamber 20a and 20b for receiving thestrong filtrate liquor and the spent wash liquor respectively.

In this embodiment the bridge plate is centered relative to thestationary valve member, and thus also relative to the trunnion axis, bymeans of a 'bolt 58 (see FIGS. 7 and 8) threaded into partition 57 (seeFIG. 6).

In FIG. 6 with the filter rotating in the direction of arrow K thesetting of the bridge blocks individually and the setting of the bridgeplate assembly as a whole, provide an example of a filtration cyclewhich comprises:

(a) a first neutral zone Z-l (between points A and B);

(b) a blowback cake discharge zone Z-Z (between points B and C);

(c) a second neutral zone Z-3 (between points C and D);

(d) a first vacuum or cake formation zone Z-4 (between ponts D and E);

(e) a third neutral zone Z- between points E and F);

(f) a second vacuum or cake washing and/or drying zone Z-6 (betweenpoints F and A).

An index device 1-1 is for the purpose of registering the angularposition of the bridge plate relative to the trunnion bearing 14. Thedevice therefore comprises an arched element or curved steel strap 59having its end fastened or clamped to respective horizontal bolts 50(see FIG. 6), and bearing a scale or index plate 60 cooperating with apointer 61 fixed upon the bridge plate 25. A companion index member 62for the pointer is shown to be settable on the index plate in the mannerand for the purpose described above for the other index devices in FIG.6.

Another embodiment of the bridge plate assembly according to FIGS. and11, differs from the embodiment of FIGS. 6 and 9 insofar as the cakeformation zone merges with a subsequent cake washing and/or drying zoneinto a single large zone Z-7 effective between end points E-l and 5-2.

This then provides a single large throughfiow passage area or opening 0for the joint volumes of filtrate liquor and spent wash liquor to becollected in a single vacuum receiver. Other-wise, the filtration cycleand the adjustment means in this embodiment may be the same as thosedescribed above for the embodiment of FIGS. 6 and 9. Furthermore, in theembodiment of FIGS. 10, 10a, and 11 an index device 1-2 for registeringthe position of the bridge plate assembly relative to the trunnionbearing, comprises an index plate 63 press-fitted into a peripheralgroove 64 on the brdige plate 65 and cooperating with a pointer 66mounted on the trunnion bearing 14.

Groove 64 also holds index plates 67 and 68 of index devices I3 and 1-4of associated bridge blocks 69 and 70 respectively. These bridge blocksare adjustable substantially in the manner above described, in a shallowgroove defined by an outer peripheral rim portion 71 of the bridgeplate, and by an inner semi-cylindrical wall portion 72 concentric withthe rim portion and connected rigidly thereto by the flat bottom portion73 of the groove.

I claim:

1. A trunnion valve for rotary filters having a horizontal axis ofrotation and having a pressure differential cakeforming zone, a pressuredifferential drying zone and a backblow cake discharge zone, comprisingin combination, a trunnion supporting the filter for rotation, saidtrunnion having an end face, filtrate discharge ducts in the trunnion astationary valve member having an end face parallel to and in opposedrelation to said trunnion face, said valve member face having openingsconnected respectively with a source of pressure differential and asource of backblow, a bridge plate, means supporting said bridge platefor limited angular adjustment in substantially fluid tight face to facecontact with said end faces, said bridge plate having pressuredifferential and blow openings registering with the openings in saidvalve memher, and the trunnion face openings at pre-determined annularpositions thereof, the bridge plate having an annular grooveintersecting the bridge plate openings, and at least one bridge blockadjustable in the groove, whereby the extent and location of said zonesmay be varied by angular adiustment of the bridge plate and block as awhole about said axis, and by individual adjustment of the bridge blockwith respect to the bridge plate.

2. The trunnion 'valve according to claim 1, with the addition of meansextending from said bridge block through the adjoining peripheral rimportion of said bridge plate, for effecting adjustment of said block.

3. A trunnion valve for rotary filters having a horizontal axis ofrotation, and having a pressure differential cake-forming zone, apressure differential cake drying zone, and a backblow cake dischargezone, which zones are functionally separated from one another by a firstand a second neutral zone, said trunnion valve comprising a trunnion andtrunnion bearing, filtrate discharge ducts in the trunnion equallyspaced about the horizontal axis, and terminating in the end face of thetrunnion,

a stationary valve member having an end face parallel to said end faceof said trunnion, said valve member face having openings connectedrespectively with a source of pressure differential and a source ofbackblow,

a bridge plate located between said trunnion and said stationary valvemember concentric and in substantially fluid-tight face to face contacttherewith, said bridge plate member having an outer annular rim portion,and having an arcuate groove extending internally along said rimportion, said groove having an inner arcuate portion, and presenting anarcuate flow blocking area having a baclrblow opening communicating withthe backblow opening in said stationary valve member, and also defininga complementary throughfiow opening within said rim portion,communicating with the pressure differential opening in said stationaryvalve member, said outer rim portion having within the range of saidgroove an upper slotted opening elongated in the direction of theperiphery of the rim portion, and a lower similar slotted opening,

an upper bridge block fitted into said arcuate groove, and having abackblow passage opening substantially registering with said backblowopening in the groove, said bridge block being adjustable in said groovefor adjusting the end of said vacuum drying zone and the location ofsaid blowback zone respectively,

and a lower bridge block movable in said arcuate groove for adjustingthe beginning of the cake-forming zone, each of said bridge blockshaving a stem extending radially outwardly therefrom through arespective slotted opening, whereby each block is movable in said bridgeplate within a range corresponding to the extent of said slottedopenings,

securing means for fixing the adjusted position of said stems andblocks,

first fastening means operable for maintaining said bridge plate memberand said hollow valve member concentrically connected with one another,so as to constitute a sub-assembly,

and second fastening means operable to maintain said sub-assemblycooperating concentrically with said trunnion in the operation of thefiltration cycle during rotation of said trunnion and said assembly offilter chambers.

4. The trunnion valve according to claim 3, wherein said first fasteningmeans are constructed and arranged so as to allow for rotationaladjustment of said bridge plate about said axis relative to saidstationary valve member.

5. The trunnion valve according to claim 3, wherein said inner arcuateportion of the bridge plate is of substantially semi-circular shape,providing for a correspond, ingly large complementary through'flow area.

6. The trunnion valve according to claim 3, wherein said inner arcuateportion of the bridge plate member is in the shape of a substantiallysemi-cylindrical wall, providing for a correspondingly largecomplementary throughfiow area.

7. The trunnion valve according to claim 3, wherein said inner arcuateportion of the bridge plate member is provided by a hub plate portiondefining with said outer rim portion an arcuate throughfiow areacomplementary to the area closed by said blocks, wherein said outer rimportion and said hub portion each have a shoulder extending along thearcuate length of said arcuate throughflow area and co-planar with thebottom face of said arcuate groove, wherein said throughfiow area isdivided by a rib extending radially substantially horizontally betweensaid hub plate portion and said outer rim portion, and having parallelvertical end faces co-planar with the outer end face of said bridgeplate and with the faces of said shoulders respectively, and wherein athird bridge block is provided in said groove, associated with said rib,providing a third neutral zone in the filtration cycle for separatecollection of filtrate liquids derived from respective operating zonesof the filtration cycle.

8. The trunnnion valve according to claim 3, wherein said stems are inthe form of a screw bolt threaded into the respective blocks.

9. The trunnion valve construction according to claim 3, with theaddition of index means for registering the adjusted position of each ofsaid bridge blocks, comprising for each block an index scale provided onsaid outer rim portion, and a pointer member connected to the stern soas to be movable therewith, and cooperating with said index scale.

10. The trunnion valve according to claim 9, wherein said outer rimportion has an external peripheral groove, and wherein said index scalecomprises a scale plate pressfitted into said groove.

11. The trunnion valve according to claim 9, wherein said outer rimportion has an external peripheral groove, wherein said stems are in theform of a screw bolt threaded into respective blocks, with the additionof means for registering the adjusted position of each said bridgeblock, comprising for each block and index plate press-fitted into saidgroove, and a pointer member connected to the stem so as to be movabletherewith, and cooperating with said scale member.

12. The trunnion valve according to claim 11, wherein said pointermember comprises a body portion hugging the outer face of said outer rimportion, and said bolt extends through said body portion of the pointermember, so that tightening said bolt will fix said block and saidpointer member relative to said index plate.

13. The trunnion valve according to claim 3, wherein said outer rimportion has an external peripheral groove, with the addition of meansfor registering the adjusted position of each of said bridge blocks,comprising for each said block an index plate pressafitted into saidgroove, and a pointer member connected to the stem of the block so as tobe movable therewith, and cooperating with said index plate, and acompanion index member for said pointer member, settable upon said indexplate.

14. The trunnion valve according to claim 13, wherein said stemcomprises a bolt threaded into the respective block, and extendingthrough said pointer member so that tightening said bolt will fix saidblock and said pointer member in adjusted position relative to saidindex plate.

15. The trunnion valve according to claim 3, wherein said firstfastening means are constructed and arranged so as to allow forrotational adjustment of said bridge plate relative to said stationaryvalve member, with the addition of means for registering the adjustedposition of each of said bridge block, comprising for each block anindex scale provided on said outer rim portion, and a pointer memberconnected to the stem of the block so as to be movable therewith, andcooperating with said index scale, and additional index means effectivebetween said bridge plate member and said trunnion bearing, forregistering the adjusted position of said bridge plate.

16. The trunnion valve according to claim 15, wherein said additionalindex means comprise an index plate press-fitted into said peripheralgroove, and a pointer carried by said trunnion bearing, cooperating withsaid index plate.

17. In a trunnion valve for a rotary filter having a horizontal axis ofrotation, a bridge plate assembly which comprises a bridge plate memberhaving an outer annular rim portion, and having an arcuate grooveextending internally along said rim portion, said groove having an innerarcuate portion, and presenting an arcuate flow blocking area having abackblow opening, and also defining a complementary throughfiow openingwithin said rim portion, said outer rim portion having within the rangeof said groove an upper slotted opening elongated in the direction ofthe periphery of the rim portion, and a lower similar slotted opening,

an upper bridge block fitted into said arcuate groove, and having abackblow passage opening substantially registering with said backblowopening in the groove, said bridge block being adjustable in saidgroove,

and a lower bridge block movable in said arcuate groove for adjustingthe beginning of the cakeforming zone, each of said bridge blocks havinga stern extending radially outwardly therefrom through a respectiveslotted opening, whereby each block is movable in said bridge platewithin a range corresponding to the extent of said slotted openings,

and securing means for fixing the adjusted position of said stems andblocks.

18. The bridge plate assembly according to claim 17, wherein said firstfastening means are constructed and arranged so as to allow forrotational adjustment of said bridge plate member about said axisrelative to said stationary hollow valve member.

19. The bridge plate assembly according to claim 17, wherein said innerarcuate portion of the bridge plate member is in the shape of asubstantially semi-cylindrical wall, providing for a correspondinglylarge complementary throughfiow area.

20. The bridge plate assembly according to claim 17, wherein said innerarcuate portion of the bridge plate member is provided by a hub plateportion defining with said outer rim portion an arcuate throughfiow areacomplementary to the area closed by said blocks, wherein said outer rimportion and said hub portion each have a shoulder extending along thearcuate length of said arcuate throughfiow area, and co-planar with thebottom face of said arcuate groove, wherein said throughfiow area isdivided by a rib extending radially substantially horizontally betweensaid hub plate portion and said outer rim portion, and having parallelvertical end faces co-planar with the outer end face of said bridgeplate member and with the faces of said shoulders respectively, andwherein a third bridge block is provided in said groove, associated withsaid rib, providing a third neutral zone in the filtration cycle forseparate collection of filtrate liquids derived from respectiveoperating zones of the filtration cycle.

21. The bridge plate assembly according to claim 17, wherein said stemsare in the form of a screw bolt threaded into the respective blocks.

22. The bridge plate assembly according to claim 17, wherein said innerarcuate portion of the bridge plate is of substantially semi-circularshape such as to provide for a correspondingly large complementarythroughfiow area.

23. The bridge plate assembly according to claim 22, wherein said outerrim portion has an external peripheral groove, with the addition ofmeans for registering the adjusted position of each of said bridgeblocks, comprising for each said block an index plate press-fitted intosaid groove, and a pointer member connected to the stem of the block soas to be movable therewith, and cooperating with said index plate, and acompanion index member for said pointer member, settable upon said indexlate.

p 24, The bridge plate assembly according to claim 23, wherein said stemcomprises a bolt threaded into the respective block, and extendingthrough said pointer member so that tightening said bolt will fix, saidblock and said pointed member in adjusted position relative to saidindex plate.

25. The bridge plate assembly according to claim 17, wherein said firstfastening means are constructed and arranged so as to allow forrotational adjustment of said bridge plate relative to said stationaryvalve member, with the addition of means for registering the adjustedposition of each of said bridge block, comprising for each block anindex scale provided on said outer rim portion, and a pointer memberconnected to the stem of the block so as to be movable therewith, andcooperating with said index scale, and additional index means effectivebetween said bridge plate member and said trunnion bearing, forregistering the adjusted position of said bridge plate member.

26. The bridge plate assembly according to claim 25, wherein saidadditional index means comprise an index plate press-fitted into saidperipheral groove, and a pointer carried by said trunnion bearing,cooperating with said index plate.

27. The bridge plate assembly according to claim 17, with the additionof index means for registering the adjusted position of each of saidbridge blocks, comprising for each block an index scale provided on saidouter rim portion, and a pointer member connected to the stem so as tobe movable therewith, and cooperating with said index scale.

28. The bridge plate assembly according to claim 27, wherein said outerrim portion has an external peripheral groove, and wherein said indexscale comprises an index plate press-fitted into said groove.

29. The bridge plate assembly according to claim 27, wherein said outerrim portion has an external peripheral groove, wherein said stems are inthe form of a screw bolt threaded into respective blocks, with theaddition of means for registering the adjusted position of each saidbridge block, comprising for each block an index plate press-fitted intosaid groove, and a pointer member connected to the stern so as to bemovable therewith, and cooperating with said scale member.

30. The bridge plate assembly according to claim 29, wherein saidpointer member comprises a body portion hugging the outer face of saidouter rim portion, and said bolt extends through said body portion ofthe pointer member, so that tightening said bolt will fix said block andsaid pointer member relative to said index plate.

31. In a trunnion valve for a rotary filter having a horizontal axis ofrotation, a bridge plate assembly which comprises a bridge plate memberhaving an outer annular rim portion, and having an arcuate grooveextending internally along said rim portion, and presenting an arcuateflow blocking area at one side of said rim portion, and having anopening in the upper portion thereof and also defining a zhroughflowopening within said rim portion opposite to said blocking area, said rimportion having within the range of said groove an upper opening and alower opening.

an upper bridge block fitted into said arcuate groove,

and having a passage opening substantially registering with said openingin the groove, said bridge block being adjustable in said groove,

a lower bridge block movable in said arcuate groove for adjusting thebeginning of the cake forming zone, said bridge blocks and upper andlower openings in 10 the rim portion being constructed and arrangedrelative to each other so that said bridge blocks are accessible andadjustable through the respective upper and lower openings,

and means for securing the position of said blocks.

32. The bridge plate assembly according to claim 31, with the additionof detachable closure means for said upper and lower openings.

33. The bridge plate assembly according to claim 31, wherein at leastone of said bridge blocks has a projection extending into the associatedopening and operable for adjustment of the blocks, said projection andsaid opening being dimensioned relative to each other so as to allow forsaid adjustment.

34. In a trunnion valve for a rotary filter having a horizontal axis ofrotation, a bridge plate assembly which comprises a bridge plate memberhaving an outer annular rim portion, and having an arcuate grooveextending internally along said rim portion, and presenting an arcuateflow blocking area at one side of said rim portion, and having anopening in the upper portion thereof, and also defining a throughflowopening within said rim portion, opposite said blocking area, said rimportion having within the range of said groove an upper opening,

an upper bridge block fitted into said arcuate groove,

and having a passage opening substantially registering with said openingin the groove, said bridge block being adjustable in said groove, saidbridge block and said upper opening being constructed and arrangedrelative to each other so that said upper bridge block is accessible andadjustable through said upper opening, means for securing the positionof said upper block,

a lower bridge block movable in said arcuate groove for adjusting thebeginning of the cake forming zone,

and means for securing the position of said lower block,

35. In a trunnion valve for a rotary filter having a horizonal axis ofrotation, a bridge plate assembly which comprises a bridge plate memberhaving an outer annular rim portion, and having an arcuate grooveextending internally along said rim portion, and presenting an arcuateflow blocking area at one side of said rim portion, and having athroughflow opening in the upper portion thereof, within said rimportion, opposite to said blocking area, said rim portion having withinthe range of said groove a lower opening,

an upper bridge block fitted into said arcuate groove,

and having a passage opening substantially registering with said openingin the groove, said bridge block being adjustable in said groove,

:1 lower bridge block movable in said arcuate groove for adjusting thebeginning of the cake forming zone, said bridge block and said loweropening being constructed and arranged relative to each other so thatsaid lower bridge block is accessible and adjustable through said loweropening,

and means for securing the positions of said blocks.

36. A trunnion valve for rotary filters having a horizontal axis ofrotation, and having a pressure difierential cake forming zone, apressure difierential cake drying zone, and a cake discharge zone, saidtrunnion valve comprising a trunnion and trunnion bearing, filtratedischarge ducts in the trunnion equally spaced about the horizontalaxis, and terminating in the end face of the trunnion,

a stationary valve member having an end face parallel to said end faceof the trunnion, said valve member face having one passage openingconnected with a source of pressure diflerential, providing vacuum, andhaving another passage opening communicating with an air supply,

a bridge plate located between said trunnion and said stationary valvemember concentric and in substantially fluid-tight face to face contacttherewith, said bridge plate member having an outer annular rim portion,and having an arcuate groove extending internally along said rimportion, and having an inner arcuate portion, and presenting an arcuateflow blocking area having a passage opening communicating with saidother passage opening in said stationary valve member. and also defininga throughflow opening within said rim portion opposite to said blockingarea, communicating with the vacuum opening in said stationary valvemember, said outer rim portion having within the range of said groove anupper opening and a lower opening,

an upper bridge block fitted into said arcuate groove,

and having a passage opening substantially registering with said otheropening in the groove, said bridge block being adjustable in said groovethrough said upper opening,

a lower bridge block movable in said arcuate groove for adjusting thebeginning of the cake forming zone, said bridge blocks and said upperand lower openings being constructed and arranged relative to each otherso that said blocks are accessible and adjustable through said upper andsaid lower opening respectively,

securing means for fixing the adjusted position of said blocks,

first fastening means operable for maintaining said bridge plate memberand said hollow valve member concentrically connected with one another,to constitute a sub-assembly,

and second fastening means operable to maintain said sub-assemblycooperating concentrically with said trunnion in the operation of thefiltration cycle during rotation of said trunnion and said filterchambers.

37. The trunnion valve according to claim 36 wherein at least one ofsaid blocks has a projection extending into the respective associatedopening in the rim portion, operable for adjusting said block.

38. The trunnion valve according to claim 36, wherein said firstfastening means are constructed and arranged so as to allow forrotational adjustment of said bridge plate about said axis relative tosaid stationary valve member.

39. In a trunnion valve for a rotary filter having a horizontal axis ofrotation, a bridge plate assembly which comprises a bridge plate memberhaving an outer annular rim portion and having an arcuate grooveextending internally along said rim portion, and presenting a flowblocking area at one side of said rim portion, and also defining athroughflow opening within said rim portion opposite to said blockingarea, said rim portion having within the range of said groove a radiallydirected upper opening,

an upper bridge block fitted into said arcuate groove, and beingadjustable in said groove and relative to said blocking area, said blockand said upper opening being constructed and arranged relative to eachother so that said upper bridge block is accessible and adjustablethrough said upper opening,

and a lower bridge block fitted into said arcuate groove, and movable insaid arcuate groove and relative to said blocking area for adjusting thebeginning of the cake forming zone.

40. In a trunnion valve for a rotary filter having a horizontal axis ofrotation, a bridge plate assembly which comprises a bridge plate memberhaving an outer annular rim portion and having an arcuate grooveextending internally along said rim portion, and presenting a flowblocking area at one side of said rim portion, and also defining athroughflow opening within said rim portion opposite to said blockingarea, said rim portion having within the range of said groove a lowerradially directed opening,

an upper bridge block fitted into said arcuate groove,

and movable for adjustment in said groove and relative to said blockingarea,

and a lower bridge block fitted into said arcuate groove,

and being adjustable in said groove and relative to said blocking areafor adjusting the beginning of the cake forming zone, said block andsaid lower opening being constructed and arranged relative to each otherso that said upper bridge block is accessible and adjustable throughsaid lower opening.

41. In a trunnion valve for a rotary filter having a horizontal axis ofrotation, a bridge plate assembly which comprises a bridge member havingan outer annular rim portion and having an arcuate groove extendinginternally along said rim portion, and presenting a through flow area,said rim portion having a radially directed opening,

at least one bridge block fitted into said arcuate groove,

and blocking a corresponding area of said through flow opening, andbeing adjustable in said groove for adjusting a respective operatingzone of a filtration cycle, said bridge block and said radially directedopening being constructed and arranged relative to each other so thatsaid block is accessible and adjustable through said radially directedopening.

42. In a trunnion valve for a rotary filter having a horizontal axis ofrotation, a bridge plate assembly which comprises a bridge plate memberhaving an outer annular rim portion and having an arcuate grooveextending peripherally along said rim portion, and presenting athroughflow area, said rim portion having a plurality radially directedspaced openings,

and a corresponding number of bridge blocks fitted into said arcuategroove, and blocking corresponding areas of said through flow opening,and being adjustable in said groove for adjusting respective operatingzone of a filtration cycle, said bridge blocks and the associatedradially directed openings being constructed and arranged relative toeach other so that said blocks are accessible and adjustable throughsaid radially directed openings.

References Cited The following references, cited by the Examiner, are ofrecord in the patented file of this patent or the original patent.

UNITED STATES PATENTS 2,289,762 7/1942 Duvall 210-404 X 2,899,068 3/1959King et al 210-404 X 3,027,011 3/1962 Flynn 210404 3,143,105 7/1965Putnam 210331 3,220,554 11/1965 Burchert et al. 210-404 X 3,409,13411/1968 Wallace et a1. 210331 X FRANK A. SPEAR, 1a., Primary ExaminerUS. Cl. X.R.

